Instream flow & water management rules

Decisions and rules affect instream flows

Rules protecting streamflows evolved over time. Early instream flow rules set instream flows for rivers and streams, established requirements for new water right permits, and often closed surface waters to new diversions.

Recently adopted rules set instream flows for rivers and streams, set up the requirements for new water uses under permits or through permit-exempt wells, and may close basins to all new unmitigated uses.

Court decisions have also affected instream flow protection. Some key examples include:

• Campbell and Gwinn — use of the groundwater permit-exemption for groups of homes.
• Foster — limits our authority in applying the overriding considerations of public interest standard and prohibits the use of out-of-kind mitigation.
• Hirst — requiring counties to independently determine water availability under the Growth Management Act.
• Postema — clarifies the impairment test and prohibits even very small impacts to instream flows.
• Swinomish — restricts applying the overriding considerations of public interest standard for establishing reserves of water for new out-of-stream uses.

Areas of the state with adopted instream flows

• Instream flow rule map

Rule implementation activities

In all basins where instream flows are adopted, we condition new water right permits to protect the instream flow levels. In some basins we are helping track allocations from water reserved for new uses. In others, as linked below, we are taking a very active role in finding or providing mitigation and reliable water supplies for rural development.

• Dungeness River basin 
• Skagit River basin 
• Spokane River and Rathdrum Prairie Aquifer